They're flesh and blood creatures, even though they are physically superior to us in every way, the sheer volatile nature of space would kill them just as easily as us. Even with the biomask creating a pressure seal around their face and by extension their lungs, they would get horribly burned by whatever star is near by. Or freeze in the lack of light.
There's also radiation but I'm not sure how resistant they are to all the different types.
Either way, point still stands. They wouldn't do much better than us being unprotected in space.